Drawing instrument



C. J. WORTH( DRAWING INSTRUMENT May M, w53

2 Sheets-Sheet l Filed June 4, 1948 Fig. 3

IN VEN TOR.

Fig.

Patented May 19, 1953 UNITED STATES `PATENT OFFICE DRAWING INSTRUMENT Charles J. Worth, New York, N. Y. Application June 4, 1948, Serial No. 31,037 r (ci. :as-17) 10 Claims.

This invention generally relates to improvements in drawing instruments facilitating the making of perspective drawings.

Heretofore, the draitsrnan had to contend with large obstructions placed on the drawing platform for use with a perspective linead. Other types of perspective lineads are inaccurate as the pivotal point is usually placed off the working edge. With the perspective lineads in use today, it is impossible for a draftsman to remove his drawing from the drawing platform and then replace it and resume drawing without a great deal of resetting of his instrument and with all the r e setting, the draftsman is rarely able to get complete accuracy.

The principal object of this invention is to aid the making of perspective drawings, and facilitate the removal and replacement ofthe drawing while not losing any accuracy.

Another object of this invention is to provide a device which will enhance the making of perspective drawings while the instrument is not unwieldy or diicult to use.

Another object is to provide a device whereby perspective drawings may be made morev easily and accurately than has heretofore been possible.

Therefore, because of its novel construction, which will be described in detail, this device is unparalleled for accuracy and ease in using. `It is small, light, compact and durable and can be used to pivotally join any size drawing instrument and drawing platform.

This device is neat in appearance, simple in design and possesses great utility in facilitating the making of perspective drawings.

Other objects and advantages will appear clear to those skilled in the art as the description proceeds and the novel features of construction, unique combination and the arrangement of parts will be more fully understood by referring to the accompanying drawings wherein:

Figure l is a plan view of a drawing board with three positions of a T-square incorporating the invention shown thereon.

Figure 2 is a partial plan view of a T-square incorporating part of the invention and a variation thereof mounted thereon.

Figure 3 is an end elevation of Figure 2.

Figure 4 is a cross-sectional elevation of the invention in a mated relationship.

Figure 5 is a cross-sectional elevation of the pivot.

Figure Sis a plan View of Figure 5. v

Figure 7 is a cross-sectional elevationof a modiflcation of Figure 5.

, Figure 8 is a cross-sectional elevation of a pivot base.

Figure 9 is a plan View of Figure 8.

Figure 10 is a plan View of a pivot base mount.

Figure 11 is a cross-sectional elevation taken on line I l--l I of Figure 10.

Figure 12 is a cross-sectional side elevation taken on line |2-I2 of Figure 11.

Figure 13 is an elevation of the modified pivot base.

In Figure l, the conventional use of a T-suuare 22 on a working edge 20a of a drawing board 26 is shown at A the drawing board 2E) having thereon a paper 2| which may have a perspective layout thereon. By the use of the invention, the T-square 22 may be pivoted at the right vision point (R. V. P.) on a pivot assembly 23 as is shown at B or at the left vision point (L. V. P.) as is shown at C on a similar pivot assembly 23.

As is shown in Figure 2, the T-square 22 may be composed of the conventional head 22a `and a T-square blade 22h joined together by screws 22e. Both the head 22a and the blade 22h are recessed to accept the pivot 4|! or the modification |140 of is to be flush with the top of the T-square blade 22h. The centerpoint of the built-up portion 44 of the pivot 4|) or |44 of the pivot |40 is on the same plane and is bisected by the working edge of the T-square blade 22h. The accuracy of the invention is directly dependent upon this assemblage. The more accurate the assembly is mounted, the more accurate the radiating lines will be. This pivot of the device will be more fully described in detail in connection with the mating pivot base of the assembly; these parts being adapted to be mated to hold the T-square in proper position for use in drawing. It should be understood that the T-square may be any type of a straight-edge while the drawing board may be any type of conventional drawing platform. The use of a T-square and drawing board is just the preferred form in the specification.

One form of the pivot base is shown at 30 in Figures 4, 8 and 9 and comprises a downwardly extending tacklike point 3| and an upwardly eX- tending center stud 32. The pivot base 30 also has a concentric cylindrical flange 34 extending upwardly from the base portion of the assembly 3Q and separated from the stud 32 by a concentric groove33 provided to accept the flange 43 of the pivot 40 or flange |43 of the modification llil upon mating. These members of the pivot base til are to be concentric. To complete the pivot base 3l?, there is provided a flange 3E having a top bearing surface 35a,

The pivot lill shown in Figures fi, 5 and 6 is comprised or" a plate il having holes ila for receiving the mounting screws 22d and a built-up portion @to provided with a centralhole 132 adapted to accept the stud 32 of the pivot base Sil or the stud i222 of the modification i3d upon mating of these assemblies and the pivot Ml. The portion :itc has an inner concentric cylindrical flange i3 extending upwardly being accepted by the groove 33 of the pivot base 3d or groove 633 of the modification i3@ upon mating of the assemblies. Outwardly of the flange i3 is a concentric cylindrical flange id separated from the inner flange by a concentric groove 45. This flange lil surrounds the pivot base upon mating with the surface da riding on the bearing surface 35a of the flange t.

When required, the pivot and pivot base may be varied in form as is. shown in Figure for the pivot and in iigures l0, ll, l2 and 13 for the pivot base.

A modified pivot ill@ is adapted for attachment to the bottom surface of the T-square head 22a by the screws 22d extending through holes ldlc in a plate lill of the assembly. Because of the under surface attachment of the pivot lli-ti, its built-up portion Mila is deeper than the portion alla of the pivot lll. The portion lllllo has a hole m2 adapted to accept the stud 32 of the pivot base 3&3 or the stud E32 of the modification i3d, an inner concentric cylindrical flange its adapted to be received by the groove of the pivot base Si! or groove H33 of the modification i3d There is an outer concentric cylindrical flange Ulli which surrounds the pivot base when mated having a surface Mido'. which rides on the bearing surface 35a of the flange 35 of the pivot base The flange lll is separated from the inner flange |423 by a concentric groove Mii adapted to receive the ange of the pivot base il@ or flange Hdl of the modincation i3d upon mating,

The variation of the pivot base, enabling a draftsman to place his vision points a measured distance beyond the periphery of the drawing board as is shown in Figures l0, l1, 12 and 13.

The pivot base i3d, having an upwardly extending stud is separated from the concentric cylindrical flange i3d by a concentric groove |53. In place of the taclzlilre point 3l in the pivot base there is a downwardly extending threaded member lil and a winged nut lil l a used to hold and lock the pivot base it@ in place on the base mount The base mount B35 has an arm having a groove ltato accept the pivot base a slot lili/mab to accept the threaded member El and a second groove ltic to accept the winged nut l'la. The flange 636e formed around the slot i362; between grooves 36@ and i350 becomes a track which is clamped between the pivot i3@ the winged nut i3 la in locked position. The top face ltd of the arm i3d takes the place of the bearing surface 35o of the pivot base Sli.

Extending laterally in the opposite direction of the arm i3d, is the arm li having a downwardly extending tacklilie member i'l'd and a small orifice lib, both bisected by the extending centerline as is shown in Figure 10. Extending downwardly at the junction of the arms |35 and |3'l is a section |35@ having a face |35b. The face |3519 is perpendicular to the centerline` as is shown in Figure l0. At the base of member |35@ is a spring loaded arm |38 having a rounded outer edge |38a and forming a bifurcation with the arm |31. The spring tension of the arm |33 positively retains the tacklike member |3'ia in the drawing board while the face |3512` is abutting the working edge 2da of the drawing board 2li. It should be understood that all mating surfaces that have relative motion creating friction should be finished to give inherent self bearing characteristics to prevent binding.

Upon mounting the pivot base 3l), all that is done is to put the tacklike point on the Vision Ipoint and press into engagement with the drawing board 2B. When mounting the pivot base |3, there is slightly more work required. The horizon line is plotted, upon which, the vision points are located by sliding the base mount i3d on the drawing board 2B until the face |35b abuts against the working face 2da. Align the base mount i3d until the horizon line bisects the oriiice l'lb, and the Vtaclrlilre member ltlla is placed on said line. Then, by pressing on the arm lil, engage the tacklike member lllct with the drawing board 2d. rihe pivot base |33 can then be positioned on the arm 53S and locked in position with the winged nut ldlc. Using this assembly, the vision point is denitely located when it is beyond the periphery of the drawing board.

Upon mounting the pivot All or the pivot modification Edil to the T-square or other similar instruments, the top bearing surface 44a, of the pivot or llfia or" the pivot |138 is to be flush with the top of the blade, so no part is protruding beyond said surface. The `centerpoint of the built-up portion lilla of pivot 46 or `Nitot of the modification Hill is to be on the same plane as the working edge of the blade and is to be bisected by it. The pivot base 3D or the modiication |30 is placed on the left and. right vision points. When the T-square is required to be used as a perspective linead, it is turned face down so that the pivot and pivot base are mated, using the pivot at the uppermost working edge of the T-square according to the vision point at which it is to be used. All lines drawn on the top surface will radiate from the vision point being used. The bottom llange 35 of the pivot base Sill or the arm 36 of the base mount |35 will space the T-square head slightly from the drawing board and the paper while the bearing surfaces insure smooth and free swinging while the T- square is held positively in position. Thus, extra tools are eliminated, and the burdens of the draftsman are lessened.

The device functions also as a time-saving device, since'no lining up or resetting is required as the taclrlike point is always available as are the vision points. Also, vthe pivot base may be removed or the paper may be removed and be replaced Without the danger lof losing any of the accuracy of the drawing.

` The invention eliminates the large bulky blocks that are now in use as well as keeping accuracy. It gives the draftsman more speed and relief from excess and unnecessary burdens and extra instru- Iints. It helps advance and bring drafting up to Although the invention has been described in detail, and with respect to certain preferred forms thereof, it is not desired to be limited thereto since changes and modifications which will become apparent to those skilled in the art may be made therein without departing from the scope and spirit of the invention as more particularly set forth in the appended claims.

I claim:

1. In combination with a drawing instrument and a drawing platform, a pivot assembly having a pivot member attached to said drawing instrument having a built-up portion of a plurality of concentric recesses and projections capable of mating with pivot bases, said pivot bases capable of being positioned without the periphery of said drawing platform and detachably xed thereto and retained by a downwardly extending piercing member.

2. In combination with a drawing instrument and a drawing platform, a plurality of pivot members xedly attached to said drawing instrument and a plurality of pivot base members capable of mating with said pivot members, a pivot base mount portion of which part is positioned within the periphery of said drawing platform and the remaining portion of said pivot base mounting members positioned without the periphery of said drawing platform, said pivot base members being detachably mounted and retained thereto by a downwardly extending piercing member.

3. In combination with a drawing instrument and a drawing platform, a plurality of pivot members xedly attached to said drawing instrument and a plurality of pivot base members capable of mating with said pivot members and detachably joined to and retained by a downwardly extending piercing member without the periphery of said drawing platform.

4. A pivot mounting assembly, capable of mating with pivots mounted upon a drawing instrument comprising a base portion capable of being positioned and locked on a slotted laterally extending arm, having a plurality of grooves and anges, of a base mount which detachably mounts said base portion to a drawing platform, said base portion having complex means therein for the reception of the mating parts of a pivot portion secured to a drawing instrument above the drawing platform and being retained -thereto by a downwardly extending piercing member.

5. An assembly for pivotally mounting a drawing instrument to a drawing platform with the pivot point positioned substantially beyond the limits of said drawing platform, comprising a pivot member, a base member and a base mount with a slotted laterally extending arm having a plurality of flanges and grooves; said pivot member attached to said drawing instrument and having a cylindrical built-up portion capable of mating with said base member, said base member capable of being positioned and locked on the arm of the base mount detachably mounting said pivot base to said drawing platform and being retained thereto by a downwardly extending piercing member.

6. An assembly for pivotally mounting a drawing instrument to a drawing platform, comprising a cylindrical pivot member, a pivot base member and a pivot base mount having a slotted laterally extending arm, said pivot member attached to said drawing instrument, said base member having therein a plurality of concentric annular por- -tions forming channels for the reception of mating projections of said pivot member and said pivot base member capable of being secured to said drawing platform by said base mount and retained thereto by a downwardly extending piercing member.

7. In combination with a drawing platform and a drawing instrument, a pivot assembly comprising a pivot member positively attached to said drawing instrument and having a built-up portion of a4 plurality of concentric annular rings capable of mating with and rotating on a base member .which is positioned on a pivot base mount having a laterally extending slotted arm, said arm having a grooved portion about the slot in the upper and lower surfaces forming strengthening flanges on both sides of said arm, said groove in the upper surface of said arm being a housing for the lower portion `of the pivot base and the groove in the lower surface being a housing for the pivot base locking nut, the top surface of said arm being an auxiliary bearing surface for the pivot member, said pivot base mounting portion being retained by the coaction of the spring loaded bifurcated arm and the piercing member.

8. In combination with a drawing platform and a drawing instrument, a pivot assembly comprising a rst portion positively attached to said drawing instrument and having a built-up receiving section adaptable to mate with a. second portion, said second portion being so constructed as to be capable of being positioned and locked on a laterally extending slotted arm of a third member, said third member detachably mounting the second member to the drawing platform and being retained thereto by a downwardly extending piercing member.

9. A T-square in combination with a drawing platform and a plurality of pivot assemblies comprising pivots attached to said T-square and substantially flush with the top surface of the blade thereof, pivot bases and pivot base mounts, said pivot base mounts having bifurcated porti-ons and extending piercing members, which retain said base mounts to said drawing platform, and laterally extending slottedyarms having a plurality `of flanges and grooves upon which is positioned and locked said pivot bases, said pivot bases being capable of mating with said pivots.

10. A T-square, drawing platform and a pivot assembly capable of pivotally joining said T- square to said drawing platform enabling said T-square to operate normally and as a perspective linead in its inverted position pivoting upon said pivot assembly, said pivot assembly comprising a pivot attached to said T-square substantially ush with the upper surface of the blade thereof, a pivot base and a pivot base mount, said pivot base mount having a bifurcated portion and an extending member cooperating together to retain said base mount to said drawing platform, said pivot base being positioned and locked upon a laterally extending slotted arm having a plurality of flanges and grooves of said pivot base mount and being capable of mating with said pivot.

CHARLES J. WORTH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 497,147 Urich May 9, 1893 '795,065 Ring July 18, 1905 2,191,109 Kittredge Feb. 20, 1940 2,210,895 Brownjohn Aug. 13, 1940 FOREIGN PATENTS Number Country Date 208,211 Great Britain Dec. 11, 1923 236,261 Germany July 1, 1911 497,357 France Sept. 10, 1919 

